Abstract: Objective 2A14-T6 aluminum alloy exhibits high strength, high hardness, and excellent wear and deformation resistance after T6 heat treatment. Its fillet welds are widely used in aerospace and launch vehicle structures, where they bear complex loads. However, systematic tests on load-bearing capacity of such fillet welds in different directions are insufficient in China, which limits their engineering application. This paper aims to study the problem, explore scientific and effective strength evaluation methods, and provide technical support for engineering practice. Methods First, stress state of 2A14-T6 aluminum alloy fillet welds under the actual working conditions of launch vehicle structures was analyzed. Subsequently, five typical test conditions were designed, including single-weld tensile test, double-weld tensile test, T-shaped single-side fillet weld shear test, T-shaped double-side fillet weld shear test, and fillet weld tear test. Systematic research and analysis were conducted on crack location and load-bearing performance of welds under each condition. An elasto-plastic algorithm based on damage evolution was adopted to invert the unified mechanical properties of fillet welds. Results Through systematic tests, cracking characteristics of 2A14-T6 aluminum alloy fillet welds under five typical conditions were clarified, such as toe cracking mostly occurring in single-weld tensile tests and load-bearing uniformity being better under double-side shear conditions. Accurate load-bearing limit data were obtained, unified mechanical property parameters of fillet welds were successfully inverted, and effectiveness of the inversion method was verified. Conclusion A set of effective simulation evaluation methods for the strength of 2A14-T6 aluminum alloy fillet welds was established. The load-bearing reliability of such fillet welds under complex working conditions was verified, providing a scientific basis and practical guidance for their structural design, load matching, and safety assessment in engineering fields such as aerospace and launch vehicles.